docs: def prototype_adjacency(self, n_block_features, alpha):
          """Build a new graph.
  
          Doc for ".create(n_features, alpha)"
  
          Parameters
          -----------
          n_features : int
  
          alpha : float (0,1)
              The complexity / sparsity factor.
              This is (1 - alpha_0) in sklearn.datasets.make_sparse_spd_matrix
              where alpha_0 is the probability that a coefficient is zero.
  
          Returns
          -----------
          (n_features, n_features) matrices: covariance, precision, adjacency
          """
          return make_sparse_spd_matrix(
              n_block_features,
              alpha=np.abs(1.0 - alpha),
              smallest_coef=self.spd_low,
              largest_coef=self.spd_high,
              random_state=self.prng,
          )